This invention applies to the industry concerned with guidance and propulsion of heavy loads from place to place about a floor. This is a fluid bearing industry where loads levitate upon a near frictionless pressurized fluid plenum during transport. More particularly, this invention relates to the integration of a guide wheel function with the ground rubbing brake function within one assembly. Prior inventions include guide wheels that have connected a braking function that does not include ground contact. Examples of prior art include a wheel with disc brakes and a wheel with shoe brakes. A specific example of a similar guide wheel with a non ground contacting braking function used in the fluid levitated load industry includes that disclosed in U.S. Pat. No. 4,427,086 by Coiselet Jan. 24, 1984.
The wheel with integrated brake assembly of my invention includes a braking pad that does rub on the ground to slow the levitated load.
Since loads levitate upon a nearly frictionless fluid cushion, it takes surprisingly low forces to move load. On level floors, relatively smaller loads move by a human operator pushing or pulling on load. Heavier loads often move with a motorized transporter. A problem is not so much in getting load to move, but to stop its inertia safely once it gets moving, especially down a slight grade. Prior art inventions have solved the stopping problem by attaching a ground rubbing brake assembly to the bottom of the load. Representative prior art ground rubbing brake invention includes that disclosed in U.S. Pat. No. 3,752,331 by Colburn Aug. 14, 1973.
Sometimes it is most difficult to guide load in the direction of motion desired by the operator. Even the slightest uneven floor condition and cause the load to drift laterally. Prior art inventions have solved the guiding problem by attaching a guide wheel assembly under the load. Both the brake assembly and the guide wheel assembly are expensive. Both assemblies take significant effort to attach to load and to plumb to the pressurized fluid supply. Both assemblies together are difficult to attach to load. Usually there is minimal available space under load that is unoccupied either by the fluid bearing devices or by some other load structure feature. It is often difficult enough to find the space to attach either a brake assembly or a guide wheel assembly, without having to find space to attach both assemblies.
Some inventions in this industry disclose a guide wheel that is brakeable with conventional type structures such as disc brake or shoe brake. The fluid bearing industry rarely uses these structures. One reason for their limited use is that fluid bearings levitating the load are relatively thin. The bearing""s thickness is approximately two and one half inches. This same thickness usually dictates the distance from the floor to the bottom of load. The wheel with conventional brake shoe or disc would be most difficult and expensive to manufacture with a two and one half inch overall thickness. The solution is not practical to place the wheel outbound of the load. The load area footprint is usually quite large, and adding inches would make transport around doorways and aisles unduly difficult. An example of an outbound wheel disclosed invention is U.S. Pat. No. 3,586,118 by Bertin Jun. 22, 1971. Finally, the wheel with disc brake to be effective has be quite robust in design. The wheel assembly is very thick and made of heavy components. This is necessary to absorb the energies involved in stopping the inertia of say a typical moving 15,000 pound load. Such wheel and brake combinations would be very expensive and large and would appear similar to those used on an automobile. Typical brakes used in the fluid caster industry use a pressure actuated ground rubbing pad for purposes of thin profile to fit beneath load and for low manufacturing cost.
My invention has the object of integrating the rubbing brake function with the guide wheel function within one assembly while maintaining the thinness necessary to fit beneath the load. Additional unexpected advantages resulted: The cost of the integrated assembly is much less than the cost of the separate assemblies. The attachment footprint of the integrated assembly is much less than the footprint of the separate assemblies. Plumbing the integrated assembly to a pressurized fluid supply is easier. Attachment of the integrated assembly to the load is easier. The weight of the integrated assembly is less.
My invention integrates a ground rubbing brake assembly with a guide wheel assembly. The combined assembly results in a unique device that both stops a moving load levitated with fluid cushions and guides the load in a direction desired by the operator. The integrated brake and wheel assembly retains the thinness necessary to fit beneath load.
Many unexpected advantages result from the combination invention. My invention is about half size of the prior art brake assembly, plus guide wheel assembly. My invention is about half the weight of the prior art brake assembly, plus guide wheel assembly. My invention has almost half the parts of the prior art brake assembly, plus guide wheel assembly. My invention is much lower in cost than the prior art brake assembly, plus guide wheel assembly. My invention requires one less hose to interconnect to the pressure supply. For about the same price of either a brake assembly alone or a guide wheel assembly alone, a user can purchase my invention with both functions. Setup of my invention is easier as it has one less hose to connect. My invention requires about half the size footprint area under the load. My invention requires about half the holes and bolt connections of the brake assembly, plus guide wheel assembly.